Magnetic sensor, and a current sensor and position detection device using a magnetic sensor

ABSTRACT

A magnetic sensor comprises a magnetoresistive effect element including a first side surface and a second side surface facing in opposite directions along a first axis and a first end surface and a second end surface facing in opposite directions along a second axis substantially orthogonal to the first axis. The sensor has a sensitivity axis extending in a direction of the first axis, a first yoke unit provided adjacent to the first side surface of the magnetoresistive effect element, and a first bias magnetic field generation unit provided adjacent to the first end surface of the magnetoresistive effect element. The first bias magnetic field generation unit is provided to be capable of applying a bias magnetic field on the magnetoresistive effect element and the first yoke unit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. UtilityApplication No. 17/350,558 filed on Jun. 17, 2021, which is based on andclaims priority to Japanese Patent Application No. 2020-143495 filed onAug. 27, 2020, the contents of which are incorporated herein byreference.

BACKGROUND

The present invention relates to a magnetic sensor and a current sensorand a position detection device using this magnetic sensor.

In recent years, a physical quantity detection device (a positiondetection device) has been used for detecting physical quantities (forexample, the position and movement amount (change amount) caused by therotational movement or linear movement of a moving body, or the like) ina variety of applications. As this physical quantity detection device,one equipped with a magnetic sensor capable of detecting change in anexternal magnetic field has been known, and a sensor signalcorresponding to change in the external magnetic field is output fromthe magnetic sensor. In addition, a current sensor or the like has beenknown that has been used in control or the like of the input/outputcurrent of a battery in a hybrid electric vehicle (HEV) or electricvehicle (EV) or the like, for example, and that measures theinput/output current flowing in a conductor such as a bus bar or thelike connected to the battery. As this current sensor, one has beenknown that is provided with a magnetic sensor capable of detecting amagnetic field generated by current flowing in a conductor such as a busbar or the like.

The magnetic sensor has a magnetic sensor element that detects themagnetic field to be detected, and as the magnetic sensor element, amagnetoresistive effect element (an AMR element, GMR element, TMRelement or the like), the resistance of which changes in accordance withchange in the external magnetic field or the like is known. AMR elementshave a ferromagnetic layer exhibiting an anisotropic magnetoresistiveeffect, and the resistance value of the AMR element changes due to themagnetization direction of the ferromagnetic layer changing by applyingan external magnetic field. GMR elements and TMR elements are composedwith a layered structure having at least a free layer, the magnetizationdirection of which is caused to change in accordance with the externalmagnetic field, a magnetization fixed layer, the magnetization directionof which is fixed, and a nonmagnetic layer interposed between the freelayer and the magnetization fixed layer. In GMR elements and TMRelements, the resistance value of the GMR element and TMR element isdetermined by the angle formed by the magnetization direction of thefree layer and the magnetization direction of the magnetization fixedlayer. Furthermore, the resistance value of a GMR element and a TMRelement changes as the angle formed by the magnetization direction ofthe free layer and the magnetization fixed layer changes due to changesin the magnetization direction of the free layer in accordance with theexternal magnetic field. In magnetic sensors containing AMR elements,GMR elements or TMR elements, a sensor signal is output in accordancewith changes in the external magnetic field due to changes in theabove-described resistance value.

In a magnetic sensor having the above-described magnetoresistive effectelement, stabilization of the magnetization of the above-describedferromagnetic layer and free layer is important for a highly accuratesensor signal to be stably output. To increase stability of themagnetization of the ferromagnetic layer in AMR elements or the freelayer in GMR elements or TMR elements, a magnetic sensor has been knownthat contains a magnet to apply a bias magnetic field on theferromagnetic layer or the free layer.

PATENT LITERATURE

PATENT LITERATURE 1 Patent No. 6610746

By having a magnet that applies the above-described bias magnetic field,and by applying the bias magnetic field on the ferromagnetic layer ofthe AMR element or the free layer of the GMR element or TMR element, theaccuracy of the sensor signal output from the magnetic sensor isimproved. On the other hand, accompanying progress in increasing theperformance of applications that use magnetic sensors, proposals formagnetic sensors capable of outputting more accurate and more stablesensor signals are currently desired.

In consideration of the foregoing, it is an object of the presentinvention to provide a magnetic sensor capable of outputting highlyaccurate and stable sensor signals and to provide a current sensor andposition detection device that use such a magnetic sensor.

SUMMARY

In order to resolve the above-described problem, the present inventionprovides a magnetic sensor that includes a magnetoresistive effectelement including a first side surface and a second side surface facingin opposite directions along a first axis, and a first end surface and asecond end surface facing in opposite directions along a second axissubstantially orthogonal to the first axis, and having a sensitivityaxis extending in a direction of the first axis, a first yoke unitprovided adjacent to the first side surface of the magnetoresistiveeffect element, and a first bias magnetic field generation unit providedadjacent to the first end surface of the magnetoresistive effectelement, wherein the first bias magnetic field generation unit isprovided so as to be capable of applying a bias magnetic field on themagnetoresistive effect element and the first yoke unit.

The length of the first bias magnetic field generation unit in the firstdirection may be longer than the sum of the lengths of themagnetoresistive effect element and the first yoke unit in the firstdirection, and the magnetoresistive effect element and the first yokeunit may be provided to fit in the range of the length of the first biasmagnetic field generation unit in the first direction.

The magnetic sensor may further comprise a second yoke unit providedadjacent to the second side surface of the magnetoresistive effectelement, the length of the first bias magnetic field generation unit inthe first direction may be longer than the sum of the lengths of themagnetoresistive effect element, the first yoke unit and the second yokeunit in the first direction, and the magnetoresistive effect element,the first yoke unit and the second yoke unit may be provided so as tofit in the range of the length of the first bias magnetic fieldgeneration unit in the first direction.

The magnetic sensor may further comprise a plurality of themagnetoresistive effect elements, wherein the magnetoresistive effectelements and either one of the first yoke unit or the second yoke unitare arranged alternatingly along the first direction. The magneticsensor may further comprise a second bias magnetic field generation unitprovided adjacent to the second end surface of the magnetoresistiveeffect element, the second bias magnetic field generation unit may touchthe second end surface of the magnetoresistive effect element, and thesecond bias magnetic field generation unit may face the second endsurface of the magnetoresistive effect element with a prescribed gap inbetween.

The first bias magnetic field generation unit may touch the first endsurface of the magnetoresistive effect element, and the first biasmagnetic field generation unit may face the first end surface of themagnetoresistive effect element with a prescribed gap in between. Thefirst bias magnetic field generation unit may have a first facingsurface facing the first end surface of the magnetoresistive effectelement, the first facing surface may be inclined at a prescribed anglewith respect to a third direction orthogonal to the first direction andthe second direction, and the edge of the first end surface side of themagnetoresistive effect element may overlap the edge of the first facingsurface side of the first bias magnetic field generation unit whenviewed along the third direction.

The magnetic sensor may further comprise a second bias magnetic fieldgeneration unit provided adjacent to the second end surface of themagnetoresistive effect element, the second bias magnetic fieldgeneration unit may have a second facing surface facing the second endsurface of the magnetoresistive effect element, the second end surfacemay be inclined at a prescribed angle with respect to the thirddirection orthogonal to the first direction and the second direction,and the edge of the second end surface side of the magnetoresistiveeffect element may overlap the edge of the second facing surface sidewhen viewed along the third direction.

The first bias magnetic field generation unit may have a facing surfacethat faces the first end surface of the magnetoresistive effect elementand a protruding part that protrudes toward the first end surface of themagnetoresistive effect element from the facing surface. The magneticsensor may further comprise a second bias magnetic field generation unitprovided adjacent to the second end surface of the magnetoresistiveeffect element, and the second bias magnetic field generation unit mayhave a facing surface that faces the second end surface of themagnetoresistive effect element and a protruding part that protrudestoward the second end surface of the magnetoresistive effect elementfrom the facing surface.

The magnetoresistive effect element may include a laminated body inwhich at least a magnetization fixed layer the magnetization of which isfixed, and a magnetization free layer the magnetization direction ofwhich changes in accordance with an external magnetic field, arelayered, and may be an AMR element, a GMR element or a TMR element.

The present invention provides a position detection device comprising amagnetic detection unit that outputs a detection signal based on changein an external magnetic field accompanying movement of a moving body,and a position detection unit that detects the position of the movingbody based on the detection signal output from the magnetic detectionunit, wherein the magnetic detection unit includes the above-describedmagnetic sensor.

The present invention provides a current sensor comprising a magneticdetection unit that detects magnetism generated from a conductor inwhich a current to be measured flows, wherein the magnetic detectionunit includes the above-described magnetic sensor.

With the present invention, it is possible to provide a magnetic sensorcapable of outputting more accurate and more stable sensor signals, anda current sensor and position detection device that use such a magneticsensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing the schematic configuration of a firstaspect of a magnetic sensor according to an embodiment of the presentinvention.

FIG. 2A is a cross-sectional view showing the schematic configuration ofthe first aspect of the magnetic sensor according to the embodiment ofthe present invention.

FIG. 2B is a cross-sectional view showing the schematic configuration ofa variation of the first aspect of the magnetic sensor according to theembodiment of the present invention.

FIG. 3A is a partial enlarged plan view showing the schematicconfiguration of the first aspect of the magnetic sensor according tothe embodiment of the present invention.

FIG. 3B is a partial enlarged plan view showing the schematicconfiguration of a variation of the first aspect of the magnetic sensoraccording to the embodiment of the present invention.

FIG. 3C is a partial enlarged plan view showing the schematicconfiguration of a variation of the first aspect of the magnetic sensoraccording to the embodiment of the present invention.

FIG. 4 is a partial enlarged cross-sectional view showing the schematicconfiguration of the first aspect of the magnetic sensor according tothe embodiment of the present invention.

FIG. 5 is a plan view showing the schematic configuration of a secondaspect of a magnetic sensor according to the embodiment of the presentinvention.

FIG. 6 is a cross-sectional view showing the schematic configuration ofthe second aspect of the magnetic sensor according to the embodiment ofthe present invention.

FIG. 7A is a partial enlarged plan view showing the schematicconfiguration of the second aspect of the magnetic sensor according tothe embodiment of the present invention.

FIG. 7B is a partial enlarged plan view showing the schematicconfiguration of a variation of the second aspect of the magnetic sensoraccording to the embodiment of the present invention.

FIG. 7C is a partial enlarged plan view showing the schematicconfiguration of a variation of the second aspect of the magnetic sensoraccording to the embodiment of the present invention.

FIG. 8A is a partial enlarged cross-sectional view showing the schematicconfiguration of the second aspect of the magnetic sensor according tothe embodiment of the present invention.

FIG. 8B is a partial enlarged cross-sectional view showing the schematicconfiguration of the second aspect of the magnetic sensor according tothe embodiment of the present invention.

FIG. 9 is a plan view showing the schematic configuration of a thirdaspect of a magnetic sensor according to the embodiment of the presentinvention.

FIG. 10A is a cross-sectional view showing the schematic configurationof the third aspect of the magnetic sensor according to the embodimentof the present invention.

FIG. 10B is a cross-sectional view showing the schematic configurationof a variation of the third aspect of the magnetic sensor according tothe embodiment of the present invention.

FIG. 11A is a partial enlarged plan view showing the schematicconfiguration of the third aspect of the magnetic sensor according tothe embodiment of the present invention.

FIG. 11B is a partial enlarged plan view showing the schematicconfiguration of a variation of the third aspect of the magnetic sensoraccording to the embodiment of the present invention.

FIG. 11C is a partial enlarged plan view showing the schematicconfiguration of the third aspect of the magnetic sensor according tothe embodiment of the present invention.

FIG. 11D is a partial enlarged plan view showing the schematicconfiguration of a variation of the third aspect of the magnetic sensoraccording to the embodiment of the present invention.

FIG. 12A is a partial enlarged cross-sectional view showing theschematic configuration of a variation of the third aspect of themagnetic sensor according to the embodiment of the present invention.

FIG. 12B is a partial enlarged cross-sectional view showing theschematic configuration of a variation of the third aspect of themagnetic sensor according to the embodiment of the present invention.

FIG. 13A is a cross-sectional end view showing the schematicconfiguration of one aspect of a magnetoresistive effect element in theembodiment of the present invention.

FIG. 13B is a cross-sectional end view showing the schematicconfiguration of another aspect of a magnetoresistive effect element inthe embodiment of the present invention.

FIG. 14 is a plan view for describing the action effect of the firstaspect of the magnetic sensor according to the embodiment of the presentinvention.

FIG. 15 is a plan view for describing the action effect of the secondaspect of the magnetic sensor according to the embodiment of the presentinvention.

FIG. 16 is a plan view for describing the action effect of the thirdaspect of the magnetic sensor according to the embodiment of the presentinvention.

FIG. 17 is a perspective view showing the schematic configuration of aposition detection device according to the embodiment of the presentinvention.

FIG. 18 is a block diagram showing the schematic configuration of theposition detection device according to the embodiment of the presentinvention.

FIG. 19 is a circuit diagram schematically showing the circuitconfiguration of a magnetic sensor unit in the embodiment of the presentinvention.

FIG. 20 is a perspective view showing the schematic configuration of acurrent sensor according to the embodiment of the present invention.

FIG. 21 is a block diagram showing the schematic configuration of thecurrent sensor according to the embodiment of the present invention.

FIG. 22 is a plan view showing the schematic configuration of anotheraspect of the magnetic sensor according to the embodiment of the presentinvention.

FIG. 23 is a graph showing simulation results for the sensitivity of themagnetic sensors according to Test Examples 1-6.

FIG. 24 is a graph showing simulation results for the hysteresis of theoutput signal of the magnetic sensors according to Test Examples 1-6.

FIG. 25 is a graph showing simulation results for the sensitivity of themagnetic sensors according to Test Example 7 and Test Example 8.

FIG. 26 is a graph showing simulation results for the hysteresis of theoutput signal of the magnetic sensors according to Test Example 7 andTest Example 8.

DETAILED DESCRIPTION

Below, the best mode for implementing the magnetic sensor of the presentinvention is described with reference to the drawings. FIG. 1 is a planview showing the schematic configuration of the first aspect of amagnetic sensor according to this embodiment, FIG. 2A is across-sectional view showing the schematic configuration of the firstaspect of the magnetic sensor according to this embodiment, FIG. 2B is across-sectional view showing the schematic configuration of a variationof the first aspect of the magnetic sensor according to this embodiment,FIG. 3A is a partial enlarged plan view showing the schematicconfiguration of the first aspect of the magnetic sensor according tothis embodiment, FIG. 3B and FIG. 3C are partial enlarged plan viewsshowing the schematic configuration of variations of the first aspect ofthe magnetic sensor according to this embodiment, and FIG. 4 is apartial enlarged cross-sectional view showing the schematicconfiguration of the first aspect of the magnetic sensor according tothis embodiment.

In describing this embodiment, the “X direction, Y direction and Zdirection” are stipulated when necessary in some of the drawings. Here,the X direction and the Y direction in this embodiment are substantiallyorthogonal to each other (the angle of intersection of the X directionand the Y direction is within the range of 85˜95°) within the plane ofthe substrate (within a plane substantially parallel to the firstsurface and the second surface of the substrate), and the Z direction isthe direction of thickness of the substrate (a direction orthogonal tothe first surface and the second surface of the substate).

The magnetic sensor 1 according to this embodiment includes amagnetoresistive effect element 2 that includes a first side surface 21and a second side surface 22, which face each other in the X directionas a first direction, and a first end surface 23 and a second endsurface 24, which face each other in the Y direction, and having an axisof sensitivity in the X direction; a first yoke unit 31 (yoke unit 3)provided adjacent to the first side surface 21 of the magnetoresistiveeffect element 2; a second yoke unit 32 (yoke unit 3) provided adjacentto the second side surface 22 of the magnetoresistive effect element 2;a first bias magnetic field generation unit 41 provided adjacent to thefirst end surface 23 of the magnetoresistive effect element 2; and asecond bias magnetic field generation unit 42 provided adjacent to thesecond end surface 24 of the magnetoresistive effect element 2.

In this embodiment, the magnetoresistive effect element 2, the firstyoke unit 31, the second yoke unit 32, the first bias magnetic fieldgeneration unit 41 and the second bias magnetic field generation unit 42may be provided on a first surface of a substrate (for example, asemiconductor substrate such as a silicon wafer; a ceramic substratesuch as an AlTiC substrate, an alumina substrate or the like; a resinsubstrate; a glass substrate or the like; omitted from the drawings)having a first surface and a second surface opposite thereto, via aninsulating sublayer or the like made of Al₂O₃ or the like. The firstsurface of the substrate is a surface parallel to the XY plane thatincludes the X direction and the Y direction, and the Z direction is adirection orthogonal to the first surface of the substrate.

As the magnetoresistive effect element 2 in this embodiment, an MRelement such as an AMR element (anisotropic magnetoresistive effectelement) having a ferromagnetic layer that exhibits an anisotropicmagnetoresistive effect, a GMR element (giant magnetoresistive effectelement), TMR element (tunnel magnetoresistive effect element) or thelike can be used. The GMR element or TMR element as the magnetoresistiveeffect element 2 is, for example, a laminated body that has aspin-value-type film structure and includes a magnetization fixed layer201, a nonmagnetic layer 202 and a free layer 203, layered in that orderfrom the substrate side (see FIG. 13A). The magnetization fixed layer201 is a laminated ferri structure including a first ferromagnetic layer2011, a nonmagnetic intermediate layer 2012 and a second ferromagneticlayer 2013 and is a so-called self-pinned fixed layer (synthetic ferripinned layer, or SFP layer) in which the first ferromagnetic layer 2011and the second ferromagnetic layer 2013 are antiferromagneticallycoupled. In the magnetization fixed layer 201 (SFP layer), the firstferromagnetic layer 2011 near the nonmagnetic layer 202 can be referredto as a reference layer because this layer becomes a reference for theangle of rotation of the magnetization direction of the free layer 203.The magnetoresistive effect element 2 may be a laminated body thatincludes the free layer 203, the nonmagnetic layer 202 and themagnetization fixed layer 201, layered in that order from the substrateside. In addition, the magnetoresistive effect element 2 may be alaminated body in which an antiferromagnetic layer 204, themagnetization fixed layer 201 comprising one layer of the ferromagneticlayer, the nonmagnetic layer 202 and the free layer 203 are layered inthat order (see FIG. 13B). The antiferromagnetic layer 204 is made of anantiferromagnetic material and serves the role of fixing the directionof magnetization of the magnetization fixed layer 201 by being exchangecoupled with the magnetization fixed layer 201.

When the magnetoresistive effect element 2 is a TMR element, thenonmagnetic layer 202 is a tunnel barrier layer. When themagnetoresistive effect element 2 is a GMR element, the nonmagneticlayer 202 is a nonmagnetic conductive layer. In the TMR element and GMRelement, the resistance value changes in accordance with the angleformed by the magnetization direction of the free layer 203 with respectto the magnetization direction of the magnetization fixed layer 201. Theresistance value is a minimum when this angle is 0° (the magnetizationdirections are parallel to each other), and the resistance value is amaximum when this angle is 180° (the magnetization directions areantiparallel to each other).

In the magnetoresistive effect element 2 that is a GMR element or a TMRelement, the magnetization direction of the free layer 203 issubstantially parallel to the Y direction, and the angle of themagnetization direction of the free layer 203 with respect to the Ydirection may be 5° or less. In addition, the magnetization direction ofthe magnetization fixed layer 201 is substantially parallel to the Xdirection, and the angle of the magnetization direction of themagnetization fixed layer 201 with respect to the X direction may be 5°or less. That is to say, the magnetization direction of the free layer203 and the magnetization layer of the magnetization fixed layer 201 aresubstantially orthogonal to each other. By having the magnetizationdirection of the free layer 203 be substantially parallel to the Ydirection and the magnetization direction of the magnetization fixedlayer 201 be substantially parallel to the X direction, themagnetization of the free layer 203 rotates when an external magneticfield in the X direction is applied on the free layer 203. Accordingly,the resistance value of the magnetoresistive effect element 2 changes.

In the plan view of the magnetic sensor 1, the magnetoresistive effectelement 2 has a roughly rectangular shape with the length W2 in the Xdirection being shorter than the length L2 in the Y direction. Thelength W2 of the magnetoresistive effect element 2 in the X direction isnot particularly limited, but for example may be on the order of 0.3˜1.5μm. The length L2 of the magnetoresistive effect element 2 in the Ydirection is not particularly limited, but for example may be on theorder of 0.6˜3.0 μm. The length T2 of the magnetoresistive effectelement 2 in the Z direction is not particularly limited, but forexample may be on the order of 0.02˜0.08 μm.

The first yoke unit 31 and the second yoke unit 32 may be made of a softmagnetic material such as NiFe, CoFe, CoFeSiB, CoZrNb or the like, forexample. The first yoke unit 31 is provided adjacent to the first sidesurface 21 of the magnetoresistive effect element 2, and the second yokeunit 32 is provided adjacent to the second side surface 22 of themagnetoresistive effect element 2. That is, in the X direction, themagnetoresistive effect element 2 is interposed in between the firstyoke unit 31 and the second yoke unit 32. Because the first yoke unit 31and the second yoke unit 32, which are provided on both sides of themagnetoresistive effect element 2 in the X direction, focus the externalmagnetic field along the X direction, it is possible to improve thesensitivity of the magnetic sensor 1.

The first yoke unit 31 and the second yoke unit 32 respectively havefirst end surfaces 311 and 321, which face the first bias magnetic fieldgeneration unit 41, and second end surfaces 312 and 322, which face thesecond bias magnetic field generation unit 42. In the first aspect ofthe magnetic sensor 1 according to this embodiment, the first endsurfaces 311 and 321 of the first yoke unit 31 and the second yoke unit32 may be positioned on substantially the same XZ plane as the first endsurface 23 of the magnetoresistive effect element 2, and the second endsurfaces 312 and 322 of the first yoke unit 31 and the second yoke unit32 may be positioned on substantially the same XZ plane as the secondend surface 24 of the magnetoresistive effect element 2. By having thiskind of configuration, it is possible to improve the sensitivity of themagnetic sensor 1. “The first end surface 23 of the magnetoresistiveeffect element 2 and the first end surfaces 311 and 321 of the firstyoke unit 31 and the second yoke unit 32 being positioned onsubstantially the same XZ plane” means that in the side view along the Xdirection, the first end surface 23 of the magnetoresistive effectelement 2 being positioned closer to the first bias magnetic fieldgeneration unit 41 than the first end surfaces 311 and 321 of the firstyoke unit 31 and the second yoke unit 32 (see FIG. 3B) is tolerated,Also, the first end surfaces 311 and 321 of the first yoke unit 31 andthe second yoke unit 32 being positioned closer to the first biasmagnetic field generation unit 41 than the first end surface 23 of themagnetoresistive effect element 2 (see FIG. 3C) is tolerated. Similarly,“the second end surface 24 of the magnetoresistive effect element 2 andthe second end surfaces 312 and 322 of the first yoke unit 31 and thesecond yoke unit 32 being positioned on substantially the same XZ plane”means that in the side view along the X direction, the second endsurface 24 of the magnetoresistive effect element 2 being positionedcloser to the second bias magnetic field generation unit 42 than thesecond end surfaces 312 and 322 of the first yoke unit 31 and the secondyoke unit 32 is tolerated. Also, the second end surfaces 312 and 322 ofthe first yoke unit 31 and the second yoke unit 32 being positionedcloser to the second bias magnetic field generation unit 42 than thesecond end surface 24 of the magnetoresistive effect element 2 istolerated. In such a case, the distance G23 between the first endsurface 23 and the first end surfaces 311 and 321 in the Y direction andthe distance between the second end surface 24 and the second endsurfaces 312 and 322 in the Y direction may be on the order of 50 nm orless.

When viewed from the side surface of the magnetic sensor 1 along the Xdirection, the position of the first end surfaces 311 and 321 of thefirst yoke unit 31 and the second yoke unit 32 in the Y direction may besubstantially the same as the position of the first end surface 23 ofthe magnetoresistive effect element 2 (free layer 203) in the Ydirection, and the first facing surface 411 of the first bias magneticfield generation unit 41 may be positioned further in the +Y directionthan the first end surface 23 of the magnetoresistive effect element 2and the first end surfaces 311 and 321 of the first yoke unit 31 and thesecond yoke unit 32. In addition, the position of the second endsurfaces 312 and 322 of the first yoke unit 31 and the second yoke unit32 in the Y direction may be substantially the same as the position ofthe second end surface 24 of the magnetoresistive effect element 2 (freelayer 203) in the Y direction, and the second facing surface 421 of thesecond bias magnetic field generation unit 42 may be positioned furtherin the -Y direction than the second end surface 24 of themagnetoresistive effect element 2 and the second facing surfaces 312 and322 of the first yoke unit 31 and the second yoke unit 32.

In the plan view of the magnetic sensor 1, the first yoke unit 31 andthe second yoke unit 32 each have a roughly rectangular shape in whichthe length W31 or W32 in the X direction is shorter than the length L31or L32 in the Y direction. The lengths W31 and W32 of the first yokeunit 31 and the second yoke unit 32 in the X direction are notparticularly limited but may be on the order of 0.3˜0.15 μm, forexample. The lengths L31 and L32 of the first yoke unit 31 and thesecond yoke unit 32 in the Y direction may be substantially the same asthe length L2 of the magnetoresistive effect element 2 in the Ydirection and may be on the order of 0.6˜3.0 μm, for example. Thelengths T31 and T32 of the first yoke unit 31 and the second yoke unit32 in the Z direction may be longer than the length T2 of themagnetoresistive effect element 2 in the Z direction and may be on theorder of 0.01˜0.06 μm, for example. When the lengths T31 and T32 of thefirst yoke unit 31 and the second yoke unit 32 in the Z direction areless than 0.01 μm, there is a concern that effectively focusing theexternal magnetic field along the X direction could become difficult,causing the sensitivity of the magnetic sensor 1 to decrease. On theother hand, when the lengths T31 and T32 in the Z direction exceed 0.06μm, the sensitivity of the magnetic sensor 1 improves but there is aconcern that hysteresis of the output signal from the magnetic sensor 1could become large.

The first bias magnetic field generation unit 41 is provided adjacent tothe first end surface 23 of the magnetoresistive effect element 2, andthe second bias magnetic field generation unit 42 is provided adjacentto the second end surface 24 of the magnetoresistive effect element 2.By having the first bias magnetic field generation unit 41 and thesecond bias magnetic field generation unit 42 provided adjacent to thefirst end surface 23 and the second end surface 24, respectively, a biasmagnetic field is applied on the free layer 203 when themagnetoresistive effect element 2 is a GMR element or TMR element and onthe ferromagnetic layer in the case of an AMR element, so in a zeromagnetic field state (the initial state in which no external magneticfield is applied on the free layer 203 or the ferromagnetic layer), itis possible to cause the magnetization direction of the free layer 203or the ferromagnetic layer to be stabilized in the Y direction.

The first bias magnetic field generation unit 41 has the first facingsurface 411 facing the first end surface 23 of the magnetoresistiveeffect element 2, and the second bias magnetic field generation unit 42has the second facing surface 412 facing the second end surface 24 ofthe magnetoresistive effect element 2. The first facing surface 411 ofthe first bias magnetic field generation unit 41 and the first endsurface 23 of the magnetoresistive effect element 2 (the free layer 203or ferromagnetic layer) may be touching or may be separated by aprescribed gap G1. The second facing surface 412 of the second biasmagnetic field generation unit 22 and the second end surface 24 of themagnetoresistive effect element 2 may be touching or may be separated bya prescribed gap G2. When the first facing surface 411 and the first endsurface 23 are separated, the respective gaps G1 and G2 between them maybe on the order of 100 nm or less, for example, and may be on the orderof 5˜100 nm, preferably on the order of 5˜50 nm. When these gaps G1 andG2 exceed 100 nm, there is a concern that the bias magnetic field is noteffectively applied the free layer 203 or the ferromagnetic layer, whichcould make it difficult to cause the magnetization direction of the freelayer 203 or the ferromagnetic layer to be stabilized in the Ydirection.

The lengths W41 and W42 of the first bias magnetic field generation unit41 and the second bias magnetic field generation unit 42 in the Xdirection may be such that the magnetoresistive effect element 2, thefirst yoke unit 31 and the second yoke unit 32 fit within the regionbetween the first bias magnetic field generation unit 41 and the secondbias magnetic field generation unit 42 (the region within the range ofthese lengths W41 and W42). That is to say, the lengths W41 and W42 ofthe first bias magnetic field generation unit 41 and the second biasmagnetic field generation unit 42 in the X direction may be at least asgreat as the sum of the lengths W2, W31 and W32 of the magnetoresistiveeffect element 2, the first yoke unit 31 and the second yoke unit 32 inthe X direction and preferably longer than this sum. When the lengthsW41 and W42 of the first bias magnetic field generation unit 41 and thesecond bias magnetic field generation unit 42 in the X direction areless than the aforementioned sum and a portion of the first yoke unit 31and/or a portion of the second yoke unit 32 protrudes in the X directionfrom the above-described region, there is a concern that applying thebias magnetic field effectively on the first yoke unit 31 and/or thesecond yoke unit 32 will be difficult. The lengths W41 and W42 of thefirst bias magnetic field generation unit 41 and the second biasmagnetic field generation unit 42 in the X direction may be on the orderof 1˜10 μm, for example.

The lengths L41 and L42 of the first bias magnetic field generation unit41 and the second bias magnetic field generation unit 42 in the Ydirection and the lengths T41 and T42 of the first bias magnetic fieldgeneration unit 41 and the second bias magnetic field generation unit 42in the Z direction are not particularly limited as long as it ispossible to apply the bias magnetic field effectively on the free layer203 or ferromagnetic layer of the magnetoresistive effect element 2. Forexample, the lengths L41 and L42 in the Y direction may be on the orderof 1˜3 μm, and the lengths T41 and T42 in the Z direction may be on theorder of 10˜50 nm.

Next, a second aspect of the magnetic sensor 1 according to thisembodiment will be described.

FIG. 5 is a plan view showing the schematic configuration of the secondaspect of the magnetic sensor according to this embodiment, FIG. 6 is across-sectional view showing the schematic configuration of the secondaspect of the magnetic sensor according to this embodiment, FIG. 7A is apartial enlarged plan view showing the schematic configuration of thesecond aspect of the magnetic sensor according to this embodiment, FIG.7B and FIG. 7C are partial enlarged plan views showing the schematicconfiguration of a variation of the second aspect of the magnetic sensoraccording to this embodiment, and FIG. 8A and FIG. 8B are partialenlarged cross-sectional views showing the schematic configuration ofthe second aspect of the magnetic sensor according to this embodiment.Parts of the configuration that are like the first aspect of themagnetic sensor 1 shown in FIGS. 1 ˜4 are labeled with the same symbolsand detailed description of such is omitted here.

As shown in FIG. 5 through FIG. 8B, in the second aspect of the magneticsensor 1 according to this embodiment, the first end surfaces 311 and321 and the second end surfaces 312 and 322 of the first yoke unit 31and the second yoke unit 32 are inclined at a prescribed angle withrespect to the XY plane that includes the X direction and the Ydirection. In addition, the first facing surface 411 of the first biasmagnetic field generation unit 41 and the second facing surface 412 ofthe second bias magnetic field generation unit 42 are inclined at aprescribed angle with respect to the XY plane that includes the Xdirection and the Y direction.

The inclination angle 83 of the first end surfaces 311 and 321 and thesecond end surfaces 312 and 322 of the first yoke unit 31 and the secondyoke unit 32, and the inclination angle 84 of the first facing surface411 of the first bias magnetic field generation unit 41 and the secondfacing surface 412 of the second bias magnetic field generation unit 42may be 20˜80°, for example, and preferably 30˜70°, and particularlypreferably, 40˜60°. By having the first yoke unit 31 and the second yokeunit 32 provided at the first side surface 21 and the second sidesurface 22, respectively, of the magnetoresistive effect element 2, itis possible to cause the first yoke unit 31 and the second yoke unit 32to focus the external magnetic field along the X direction. As a result,the sensitivity of the magnetic sensor 1 is improved. The externalmagnetic field focusing effect by the first yoke unit 31 and the secondyoke unit 32 is dependent on the lengths T31 and T32 (thicknesses) ofthe first yoke unit 31 and the second yoke unit 32 in the Z direction.That is to say, the greater the thicknesses of the first yoke unit 31and the second yoke unit 32, the more efficiently the external magneticfield can be focused in the X direction, thereby making it easier toimprove the sensitivity of the magnetic sensor 1. On the other hand, thegreater the thicknesses of the first yoke unit 31 and the second yokeunit 32, the more it becomes difficult for the bias magnetic field fromthe first bias magnetic field generation unit 41 and the second biasmagnetic field generation unit 42 to be effectively applied on the firstyoke unit 31 and the second yoke unit 32, causing the concern thathysteresis of the output signal from the magnetic sensor 1 could becomelarge. In the second aspect of the magnetic sensor 1 according to thisembodiment, the first end surfaces 311 and 321 and the second endsurfaces 312 and 322 of the first yoke unit 31 and the second yoke unit32, and the first facing surface 411 of the first bias magnetic fieldgeneration unit 41 and the second facing surface 412 of the second biasmagnetic field generation unit 42, are inclined at a prescribed angle,and through this, even if the lengths T31 and T32 of the first yoke unit31 and the second yoke unit 32 in the Z direction are sufficient tocause the sensitivity of the magnetic sensor 1 to improve, it ispossible to control the occurrence of hysteresis of the output signalfrom the magnetic sensor 1.

When viewed from the side surface of the magnetic sensor 1 along the Xdirection, the position in the Y direction of a first edge E31 of thefirst end surfaces 311 and 321 of the first yoke unit 31 and the secondyoke unit 32 may be substantially the same as the position of the firstend surface 23 of the magnetoresistive effect element 2 (the free layer203 or the ferromagnetic layer) in the Y direction, and the position inthe Y direction of a second edge E32 of the first end surfaces 311 and321 of the first yoke unit 31 and the second yoke unit 32 may be closerto the first bias magnetic field generation unit 41 than the position ofthe first end surface 23 of the magnetoresistive effect element 2 (thefree layer 203 or the ferromagnetic layer). The position in the Ydirection of a first edge E41 of the first facing surface 411 of thefirst bias magnetic field generation unit 41 may be between the positionin the Y direction of the first end surface 23 of the magnetoresistiveeffect element 2 (the free layer 203 or the ferromagnetic layer) and theposition in the Y direction of the second edge E32 of the first endsurfaces 311 and 321 of the first yoke unit 31 and the second yoke unit32. In addition, the position in the Y direction of a first edge E31 ofthe second end surfaces 312 and 322 of the first yoke unit 31 and thesecond yoke unit 32 may be substantially the same as the position of thesecond end surface 24 of the magnetoresistive effect element 2 (the freelayer 203 or the ferromagnetic layer) in the Y direction, and theposition in the Y direction of a second edge E32 of each of the firstend surfaces 312 and 322 of the first yoke unit 31 and the second yokeunit 32 may be closer to the second bias magnetic field generation unit42 than the position of the second end surface 24 of themagnetoresistive effect element 2 (the free layer 203 or theferromagnetic layer). The position in the Y direction of the first edgeE41 of the second facing surface 412 of the second bias magnetic fieldgeneration unit 42 may be between the position in the Y direction of thesecond end surface 24 of the magnetoresistive effect element 2 (the freelayer 203 or the ferromagnetic layer) and the position in the Ydirection of the second edge E32 of the first end surfaces 311 and 321of the first yoke unit 31 and the second yoke unit 32. Because themagnetoresistive effect element 2 (free layer 203 or ferromagneticlayer), the first yoke unit 31, the second yoke unit 32, the first biasmagnetic field generation unit 41 and the second bias magnetic fieldgeneration unit 42 have the above-described positional relationship inthe Y direction, and the first end surfaces 311 and 321 and the secondend surfaces 321 and 322 of the first yoke unit 31 and the second yokeunit 32 along with the first facing surface 411 of the first biasmagnetic field generation unit 41 and the second facing surface 412 ofthe second bias magnetic field generation unit 42 are inclined at theprescribed angle, the sensitivity of the magnetic sensor 1 improves andit is possible to control the occurrence of hysteresis of the outputsignal from the magnetic sensor 1.

In the plan view along the Z direction, the edge of the first endsurface 23 of the magnetoresistive effect element 2 (the free layer 203or the ferromagnetic layer) may overlap the first bias magnetic fieldgeneration unit 41. That is, the position in the Y direction of thefirst end surface 23 of the magnetoresistive effect element 2 (the freelayer 203 or the ferromagnetic layer) may be positioned further in thedirection toward the first bias magnetic field generation unit 41 (+Ydirection) than the position of the first edge E41 of the first facingsurface 411 of the first bias magnetic field generation unit 41.Similarly, the edge of the second end surface 24 of the magnetoresistiveeffect element 2 (the free layer 203 or the ferromagnetic layer) mayoverlap the second bias magnetic field generation unit 42. That is, theposition in the Y direction of the second end surface 24 of themagnetoresistive effect element 2 (the free layer 203 or theferromagnetic layer) may be positioned further in the direction towardthe second bias magnetic field generation unit 42 (−Y direction) thanthe position of the first edge E41 of the second facing surface 412 ofthe second bias magnetic field generation unit 42.

A third aspect of the magnetic sensor 1 according to this embodimentwill now be described.

FIG. 9 is a plan view showing the schematic configuration of the thirdaspect of the magnetic sensor according to this embodiment, FIG. 10A andFIG. 10B are cross-sectional views showing the schematic configurationof the third aspect of the magnetic sensor according to this embodiment,FIGS. 11A 11D are partial enlarged plan views showing the schematicconfiguration of the third aspect of the magnetic sensor according tothis embodiment, and FIG. 12A and FIG. 12B are a partial enlargedcross-sectional views showing the schematic configuration of the thirdaspect of the magnetic sensor according to this embodiment. Parts of theconfiguration that are like the first aspect and the second aspect ofthe magnetic sensor 1 are labeled with the same symbols and detaileddescription of such is omitted here.

As shown in FIG. 9 through FIG. 12B, in the third aspect of the magneticsensor 1 according to this embodiment, the first bias magnetic fieldgeneration unit 41 has a first protruding part 43 that protrudes towardthe first end surface 23 of the magnetoresistive effect element 2 alongthe Y direction from the first facing surface 411, and the second biasmagnetic field generation unit 42 has a second protruding part 44 thatprotrudes toward the second end surface 24 of the magnetoresistiveeffect element 2 along the Y direction from the second facing surface412. The first end surface 311 of the first yoke unit 31 faces the firstfacing surface 411 positioned to one side (one side in the X direction)of the first protruding part 43, and the first end surface 321 of thesecond yoke unit 32 faces the first facing surface 411 positioned to theother side (the other side in the X direction) of the first protrudingpart 43. The second end surface 312 of the first yoke unit 31 faces thesecond facing surface 412 positioned to one side (one side in the Xdirection) of the second protruding part 44, and the second end surface322 of the second yoke unit 32 faces the second facing surface 412positioned to the other side (the other side in the X direction) of thesecond protruding part 44. That is, the first end surface 23 of themagnetoresistive effect element 2 (free layer 203 or ferromagneticlayer), an edge E43 of the first protruding part 43, the first edge E31of the first yoke unit 31 and the second yoke unit 32, the first edgeE41 of the first facing surface 411 of the first bias magnetic fieldgeneration unit 41, and the second edge E32 of the first yoke unit 31and the second yoke unit 32 may be positioned in that order along the Ydirection (+Y direction) (see FIG. 12A). Similarly, the second endsurface 24 of the magnetoresistive effect element 2 (free layer 203 orferromagnetic layer), an edge E44 of the second protruding part 44, thefirst edge E31 of the first yoke unit 31 and the second yoke unit 32,the first edge E42 of the second bias magnetic field generation unit 42,and the second edge E32 of the first yoke unit 31 and the second yokeunit 32 may be positioned in that order along the Y direction (−Ydirection) (see FIG. 12B). Because the first bias magnetic fieldgeneration unit 41 has the first protruding part 43, it is possible tomake the position in the Y direction of the first end surfaces 311 and321 of the first yoke unit 31 and the second yoke unit 32 be locatedfurther in the direction toward the first bias magnetic field generationunit 41 than the first end surface 23 of the magnetoresistive effectelement 2 (free layer 203 or ferromagnetic layer). Similarly, becausethe second bias magnetic field generation unit 42 has the secondprotruding part 44, it is possible to make the position in the Ydirection of the second end surfaces 312 and 322 of the first yoke unit31 and the second yoke unit 32 be located further in the directiontoward the second bias magnetic field generation unit 42 than the secondend surface 24 of the magnetoresistive effect element 2 (free layer 203or ferromagnetic layer). As a result, it is possible to improve thesensitivity of the magnetic sensor 1 and to control the occurrence ofhysteresis of the output signal from the magnetic sensor 1.

The protrusion lengths L43 and L44 in the Y direction of the firstprotruding part 43 and the second protruding part 44 are notparticularly limited, and for example may be on the order of 0.05˜0.3μm, preferably on the order of 0.1˜0.2 μm. When these protrusion lengthsL43 and L44 are less than 0.05 μm or exceed 0.3 μm, there is a concernthat the effect of improving the sensitivity of the magnetic sensor 1and the effect of controlling the occurrence of hysteresis of the outputsignal from the magnetic sensor 1 could diminish.

As shown in FIG. 12A and FIG. 12B, the first facing surface 411 of thefirst bias magnetic field generation unit 41 may be inclined at theprescribed angle e4 with respect to the XY plane containing the Xdirection and the Y direction, and the second facing surface 412 of thesecond bias magnetic field generation unit 42 may be inclined at theprescribed angle with respect to the XY plane containing the X directionand the Y direction. In addition, the first end surfaces 311 and 321 ofthe first yoke unit 31 and the second yoke unit 32 may be inclined atthe prescribed angle 83 with respect to the XY plane containing the Xdirection and the Y direction, and the second end surfaces 312 and 322of the first yoke unit 31 and the second yoke unit 32 may be inclined atthe prescribed angle with respect to the XY plane containing the Xdirection and the Y direction.

In the third aspect shown in FIG. 9 through FIG. 12B, the entire surfacealong the Z direction of the first protruding part 43 and the secondprotruding part 44 protrudes toward the first end surface 23 of themagnetoresistive effect element 2, but this is intended to beillustrative and not limiting. For example, when the magnetoresistiveeffect element 2 is a GMR element or a TME element, the first protrudingpart 43 and the second protruding part 44 may be such that only aportion of the first bias magnetic field generation unit 41 and thesecond bias magnetic field generation unit 42 facing the free layer 203in the Y direction at least protrudes. In addition, when themagnetoresistive effect element 2 is an AMR element, the firstprotruding part 43 and the second protruding part 44 may be such thatonly a portion of the first bias magnetic field generation unit 41 andthe second bias magnetic field generation unit 42 facing theferromagnetic layer in the Y direction at least protrudes.

The operation effect of the first aspect through third aspect of themagnetic sensor according to this embodiment will now be described.FIGS. 14 ˜16 are plan views for describing the operation effect of thefirst aspect through third aspect of the magnetic sensor 1 according tothis embodiment.

As shown in FIGS. 14 ˜16, in the magnetic sensor 1 according to thisembodiment, a bias magnetic field in the Y direction is applied on thefirst yoke unit 31 and the second yoke unit 32 from the first biasmagnetic field generation unit 41 and the second bias magnetic fieldgeneration unit 42. Through this, it is possible to stabilize themagnetization M₂ of the free layer 203 or ferromagnetic layer of themagnetoresistive effect element 2 along with the magnetization M₃₁ andM₃₂ of the first yoke unit 31 and the second yoke unit 32.

The first magnetic sensor 1 according to this embodiment is such thatthe first yoke unit 31 and the second yoke unit 32 capable ofeffectively focusing external magnetic fields are provided adjacent tothe first side surface 21 and the second side surface 22 of themagnetoresistive effect element 2 with the objective of improvingsensitivity to external magnetic fields. The length (thickness) in the Zdirection of the first yoke unit 31 and second yoke unit 32 is greater(thicker) than the length (thickness) in the Z direction of the freelayer 203 or ferromagnetic layer of the magnetoresistive effect element2 to effectively focus external magnetic fields. Through this, it ispossible for external magnetic fields to be effectively focused by thefirst yoke unit 31 and the second yoke unit 32 and to improve thesensitivity of the magnetic sensor 1.

On the other hand, because the length (thickness) in the Z direction ofthe first yoke unit 31 and the second yoke unit 32 is relatively long(thick), the static magnetic field Hs from the first yoke unit 31 andthe second yoke unit 32 causes the reduced magnetic field H_(d) withrespect to the free layer 203 or ferromagnetic layer of themagnetoresistive effect element 2 to increase. In the first aspect shownin FIG. 1 through FIG. 4 , the first end surface 23 of themagnetoresistive effect element 2 (free layer 203 or ferromagneticlayer) and the first end surfaces 311 and 321 of the first yoke unit 31and the second yoke unit 32 are positioned substantially on the same XZplane, and through this it is easy to cause the reduced magnetic fieldHd to become even larger. By causing the reduced magnetic field Hd tobecome larger in this manner, it becomes easy for the direction of themagnetization M₂ of the free layer 203 or ferromagnetic layer of themagnetoresistive effect element 2 to become unstable, creating theconcern that hysteresis could easily occur in the output signal from themagnetic sensor 1. On this point, by having the first end surfaces 311and 321 and the second end surfaces 312 and 322 of the first yoke unit31 and the second yoke unit 32 be inclined at a prescribed angle withrespect to the XY plan as in the second aspect, it is possible to causethe static magnetic field Hs from the first yoke unit 31 and the secondyoke unit 32 to diminish. Consequently, it is possible to cause thereduced magnetic field Hd on the free layer 203 or ferromagnetic layerof the magnetoresistive effect element 2 to be relatively diminished, soit is possible to control the occurrence of hysteresis of the outputsignal from the magnetic sensor 1.

In the second aspect, the first end surfaces 311 and 321 and the secondend surfaces 312 and 322 of the first yoke unit 31 and the second yokeunit 32 are inclined at a prescribed angle with respect to the XY plane,so the first facing surface 411 of the first bias magnetic fieldgeneration unit 41 and the second facing surface 412 of the second biasmagnetic field generation unit 42 are also inclined at the prescribedangle. When the first facing surface 411 of the first bias magneticfield generation unit 41 and the second facing surface 412 of the secondbias magnetic field generation unit 42 are inclined in this manner, thebias magnetic field from the first bias magnetic field generation unit41 and the second magnetic field generation unit 42 diminishes.

On this point, by providing the first protruding part 43 on the firstfacing surface 411 and the second protruding part 44 on the secondfacing surface 412 as in the third aspect, it is possible for the firstend surfaces 311 and 321 and the second end surfaces 312 and 322 of thefirst yoke unit 31 and the second yoke unit 32 to be positioned more tothe first bias magnetic field generation unit 41 side and the secondbias magnetic field generation unit 42 side than the first end surface23 and the second end surface 24 of the magnetoresistive effect element2 (free layer 203). Through this, it is possible to cause the staticmagnetic field Hs from the first yoke unit 31 and the second yoke unit32 to diminish, to cause the reduced magnetic field Hd on the free layer203 or ferromagnetic layer of the magnetoresistive effect element 2 torelatively diminish, and to cause the bias magnetic field from the firstbias magnetic field generation unit 41 and the second bias magneticfield generation unit 42 to be effectively applied on themagnetoresistive effect element 2 (free layer 203 or ferromagneticlayer). As a result, it is possible to cause the sensitivity of themagnetic sensor 1 to external magnetic fields to improve and to controlthe occurrence of hysteresis of the output signal from the magneticsensor 1.

Next, a position detection device that uses the magnetic sensor 1according to this embodiment will be described. FIG. 17 is a perspectiveview showing the schematic configuration of a position detection deviceaccording to this embodiment, FIG. 18 is a block diagram showing theschematic configuration of the position detection device according tothis embodiment, and FIG. 19 is a circuit diagram schematically showingthe circuit configuration of a magnetic sensor unit according to thisembodiment.

As shown in FIG. 17 , a position detection device 100 according to thisembodiment comprises a magnetic sensor device 101 and a moving body 110capable of linear movement relative to the magnetic sensor device 101and is called a linear encoder.

As shown in FIG. 18 , the magnetic sensor device 101 includes a magneticsensor unit 102 that outputs a sensor signal based on changes in theexternal magnetic field accompanying linear movement of the moving body110, and a calculation unit 103 that calculates the amount of movementof the moving body 110 based on the sensor signal output from themagnetic sensor unit 102.

The calculation unit 103 includes an A/D (analog-digital) conversionunit 104 that converts the analog signal (sensor signal) output from themagnetic sensor unit 102 into a digital signal, and an arithmeticprocessing unit 105 that processes the digital signal converted todigital by the A/D conversion unit 104 and calculates the amount ofmovement of the moving body 110. When the arithmetic processing results(movement amount) obtained in the arithmetic processing unit 105 areoutput as an analog signal, the calculation unit 103 may further includea D/A (digital-analog) conversion unit (omitted from the drawings) onthe downstream side of the arithmetic processing unit 105.

The magnetic sensor unit 102 includes at least one magnetic detectionelement and may include a pair of magnetic detection elements connectedin series. In this case, the magnetic sensor unit 102 has a Wheatstonebridge circuit that includes a pair of magnetic detection elementsconnected in series.

As shown in FIG. 19 , the Wheatstone bridge circuit includes a powersource port V, a ground port G, a first output port E1, a second outputport E2, a first magnetic detection element R1 provided between thepower source port V and the first output port E1, a second magneticdetection element R2 provided between the first output port E1 and theground port G, a third magnetic detection element R3 provided betweenthe power source port V and the second output port E2, and a fourthmagnetic detection element R4 provided between the second output port E2and the ground port G. A power source voltage (constant current) of aprescribed size is applied on the power source port V by connecting aconstant current source, and the ground port G is connected to ground.The constant current applied on the power source port V is controlled toa prescribed current value by a driver IC not shown in the drawings.

In this embodiment, the magnetic sensor 1 (see FIGS. 1 ˜12B) accordingto this embodiment is used as all the first through fourth magneticdetection elements R1˜R4 included in the Wheatstone bridge circuit. Themagnetization of the magnetization fixed layer 201 in all themagnetoresistive effect elements 2 included in the magnet sensor 1 arefixed in the same direction (+X direction) as each other. Themagnetization of the magnetization fixed layer 201 in all themagnetoresistive effect elements 2 included in the magnetic sensor 1 maybe fixed in roughly the same direction as each other, and in this case,the magnetization direction of the magnetization fixed layer 201 in eachof the magnetoresistive effect elements 2 may be inclined at an anglewithin 10° of the +X direction. All the magnetoresistive effect elements2 have a roughly rectangular shape in the Y direction, so the free layer203 in each of the magnetoresistive effect elements 2 has shapeanisotropy in which the easy magnetization axis is the Y direction.Furthermore, a bias magnetic field from the first bias magnetic fieldgeneration unit 41 and the second bias magnetic field generation unit 42is applied on each of the magnetoresistive effect elements 2.Consequently, the magnetization directions of the free layers 203 in allthe magnetoresistive effect elements 2 in the initial state (the statein which no external magnetic field is applied) are the same as eachother and are a direction (+Y direction) orthogonal to the magnetizationdirection of the magnetization fixed layer 201. By having themagnetization direction of the magnetization fixed layer 201 and thefree layer 203 be in the above-described directions, change occurs inthe resistance values of the first through fourth magnetic detectionelements R1˜R4 in accordance with the external magnetic field in the Xdirection, and accompanying this the electric potential differencebetween the first output port E1 and the second output port E2 changesand a signal representing the change in this electric potentialdifference is output from a difference detector (omitted in thedrawings).

The signal corresponding to the electric potential difference betweenthe first output port El and the second output port E2 is output to theND conversion unit 104 from the difference detector. The ND conversionunit 104 converts the sensor signal (analog signal relating to theamount of movement of the moving body 110) output from the magneticsensor unit 102 into a digital signal, and this digital signal is inputinto the arithmetic processing unit 105.

The arithmetic processing unit 105 accomplishes arithmetic processing onthe digital signal converted from the analog signal by the ND conversionunit 104 and calculates the amount of movement of the moving body 110.The arithmetic processing unit 105 may be comprised for example of amicrocomputer, an Application Specific Integrated Circuit (ASIC), or thelike.

In the position detection device 100 according to this embodiment havingthe above-described configuration, the external magnetic field changesaccompanying linear movement of the moving body 110, the resistancevalues of the first through fourth magnetic detection elements R1˜R4 ofthe magnetic sensor unit 102 change in accordance with change in thisexternal magnetic field, and a sensor signal is output from thedifference detector in accordance with the electric potential differencebetween the first output port E1 and the second output port E2 of themagnetic sensor unit 102. Furthermore, the sensor signal output from thedifference detector is converted into a digital signal by the A/Dconversion unit 104. Following this, the amount of movement of themoving body 110 is calculated by the arithmetic processing unit 105.

In the position detection device 100 according to this embodiment, themagnetic sensor 1 possessed by the magnetic sensor unit 102 is such thatthe first bias magnetic field generation unit 41 and the second biasmagnetic field generation unit 42 are respectively provided adjacent tothe first end surface 23 and the second end surface 24 of themagnetoresistive effect element 2, and the first yoke unit 31 and thesecond yoke unit 32 are respectively provided adjacent to the first sidesurface 21 and the second side surface 22 of the magnetoresistive effectelement 2, and consequently, there is high sensitivity to change in theexternal magnetic field, and moreover it is possible to control theoccurrence of hysteresis of the signal output from the magnetic sensorunit 102. Hence, with the position detection device 100 according tothis embodiment, it is possible to detect with high accuracy the amountof movement of the moving body 110.

Next, a current sensor that uses the magnetic sensor 1 according to thisembodiment will be described. FIG. 20 is a perspective view showing theschematic configuration of a current sensor according to thisembodiment, and FIG. 21 is a block diagram showing the schematicconfiguration of the current sensor according to this embodiment of thepresent invention.

A current sensor 300 according to this embodiment controls theinput/output current or the like of a battery in a hybrid electricvehicle or the like, for example, and measures, as the current beingmeasured, the input/output current flowing in a bus bar 310 connected tothe battery, for example, and comprises the bus bar 310 and a magneticsensor device 301 that includes the magnetic sensor unit 302 providednear the bus bar 310 and a calculation unit 303 that calculates theinput/output current flowing in the bus bar 310 on the basis of a sensorsignal output from the magnetic sensor unit 302.

The calculation unit 303 includes an A/D (analog-digital) conversionunit 304 that converts the analog signal (sensor signal) output from themagnetic sensor unit 302 into a digital signal, and an arithmeticprocessing unit 305 that processes the digital signal converted todigital by the A/D conversion unit 304 and calculates the input/outputcurrent flowing in the bus bar 310. When the arithmetic processingresults (input/output current) obtained in the arithmetic processingunit 305 are output as an analog signal, the calculation unit 303 mayfurther include a D/A (digital-analog) conversion unit (omitted from thedrawings) on the downstream side of the arithmetic processing unit 305.

The magnetic sensor unit 302 includes at least one magnetic detectionelement and may contain a pair of magnetic detection elements connectedin series. In this case, the magnetic sensor unit 302 has a Wheatstonebridge circuit that includes a pair of magnetic detection elementsconnected in series (see FIG. 19 ).

A signal corresponding to the electric potential difference between thefirst output port E1 and the second output port E2 of the Wheatstonebridge circuit possessed by the magnetic sensor unit 302 is output tothe A/D conversion unit 304 from a difference detector (omitted from thedrawings). The A/D conversion unit 304 converts the sensor signal(analog signal relating to the input/output current flowing in the busbar 310) output from the magnetic sensor unit 302 into a digital signal,and this digital signal is input into the arithmetic processing unit305.

The arithmetic processing unit 305 accomplishes arithmetic processing onthe digital signal converted from the analog signal by the A/Dconversion unit 304 and calculates the input/output current flowing inthe bus bar 310. The arithmetic processing unit 305 may be comprised forexample of a microcomputer, an Application Specific Integrated Circuit(ASIC), or the like.

In the current sensor 300 according to this embodiment having theabove-described configuration, a magnetic field is generated from thebus bar 310 accompanying flowing of the input/output current in the busbar 310. The resistance values of the first through fourth magneticdetection elements R1˜R4 of the magnetic sensor unit 302 change inaccordance with the strength of the magnetic field generated from thebus bar 310. Furthermore, a sensor signal is output from the differencedetector in accordance with the electric potential difference betweenthe first output port E1 and the second output port E2 of the magneticsensor unit 302. Furthermore, the sensor signal output from thedifference detector is converted into a digital signal by the A/Dconversion unit 304. Following this, the input/output current flowing inthe bus bar 310 is calculated by the arithmetic processing unit 305.

The current sensor 300 according to this embodiment (see FIG. 20 ) canbe provided in a magnetic control device. As the magnetic control deviceaccording to this embodiment, the battery management system, inverters,converters, and the like of a hybrid electric vehicle (HEV), or electricvehicle (EV) or the like can be cited. The current sensor 300 accordingto this embodiment is used to measure the input/output current from thepower source and to output to the electric control device informationrelating to the measured current.

In the current sensor 300 according to this embodiment, the magneticsensor 1 possessed by the magnetic sensor unit 302 is such that thefirst bias magnetic field generation unit 41 and the second biasmagnetic field generation unit 42 are respectively provided adjacent tothe first end surface 23 and the second end surface 24 of themagnetoresistive effect element 2, and the first yoke unit 31 and thesecond yoke unit 32 are respectively provided adjacent to the first sidesurface 21 and the second side surface 22 of the magnetoresistive effectelement 2, and consequently, there is high sensitivity to the magneticfield generated from the bus bar 310, and moreover it is possible tocontrol the occurrence of hysteresis of the signal output from themagnetic sensor unit 302. Hence, with the current sensor 300 accordingto this embodiment, it is possible to detect with high accuracy theinput/output current flowing in the bus bar 310.

The above-described embodiment was described to facilitate understandingof the present invention and was not described to limit the presentinvention. Accordingly, each element disclosed in the above-describedembodiment shall be construed to include all design modifications andequivalents falling within the technical scope of the present invention.

In the above-described embodiment, the magnetic sensor 1 was describedby citing an aspect that includes one magnetoresistive effect element 2,the first bias magnetic field generation unit 41 and the second biasmagnetic field generation unit 42 respectively provided adjacent to thefirst end surface 23 and the second end surface 24 thereof, and thefirst yoke unit 31 and the second yoke unit 32 respectively providedadjacent to the first side surface 21 and the second side surface 22thereof, but this is intended to be illustrative and not limiting. Forexample, either of the first bias magnetic field generation unit 41 orthe second bias magnetic field generation unit 42 need not be included,and either of the first yoke unit 31 or the second yoke unit 32 need notbe included.

The magnetic sensor 1 may have a plurality of magnetoresistive effectelements 2. In this case, the plurality of magnetoresistive effectelements 2 may be lined up so that yoke units 3 (first yoke unit 31 orsecond yoke units 32) are interposed alternatingly in the X direction(see FIG. 22 ). That is to say, the magnetoresistive effect elements 2and the yoke units 3 (first yoke units 31, second yoke unit 32) arearranged alternating with each other along the X direction. In thisaspect, the lengths W41 and W42 in the X direction of the first biasmagnetic field generation unit 41 and the second bias magnetic fieldgeneration unit 42 may be large enough that all of the magnetoresistiveeffect elements 2 and all of the yoke units 3 (first yoke units 31,second yoke units 32) are contained within the region encompassed by thefirst bias magnetic field generation unit 41 and the second biasmagnetic field generation unit 42 (the region within the scope of thelengths W41 and W42).

Embodiment

Below, the present invention will be described in greater detail byciting test examples, but the present invention is in no way limited bythe below-described test examples.

TEST EXAMPLE 1

In the magnetic sensor 1 having the configuration shown in FIGS. 1 ˜4,the output signal from the magnetic sensor 1 was found throughsimulation in a case where the external magnetic field fluctuated withinthe range of −20 mT to 20 mT, and the sensitivity of the magnetic sensor1 and the hysteresis of the output signal were calculated (Sample 1).Simulation results are shown in FIG. 23 and FIG. 24 . In theabove-described simulation, the lengths (W, μm) in the X direction, thelengths (L, μm) in the Y direction, the lengths (T, μm) in the Zdirection, the volume magnetization (M, emu/cm³), the exchange couplingenergy (A, erg/cm) and the magnetic field strength (Hk, Oe) of each ofthe magnetoresistive effect element 2 (free layer 203 (FL), firstferromagnetic layer 2011 (RL), second ferromagnetic layer 2013 (PL)),the first yoke unit 31 (SY1), the second yoke unit 32 (SY2), the firstbias magnetic field generation unit 41 (HM1) and the second bias fieldgeneration unit 41 (HM2) comprising the magnetic sensor 1 are as shownin Table 1.

TABLE 1 W L T M A Hk (μm) (μm) (μm) (emu/cm³) (erg/cm) (Oe) FL 0.8 2 10800 1 × 10⁻⁶ 0 RL 0.8 2 1.8 1400 1 × 10⁻⁶ 0 PL 0.8 2 1.8 1400 1 × 10⁻⁶ 0SY1 0.5 2 10 800 1 × 10⁻⁶ 0 SY2 0.5 2 10 800 1 × 10⁻⁶ 0 HM1 4 1.75 40400 1 × 10⁻⁸ 15000 HM2 4 1.75 40 400 1 × 10⁻⁸ 15000

TEST EXAMPLE 2

Other than the length (T) in the Z direction of the first yoke unit 31(SY1) and the second yoke unit 32 (SY2) being 20 μm, the output signalfrom the magnetic sensor 1 was found through simulation the same as inTest Example 1, and the sensitivity of the magnetic sensor 1 and thehysteresis of the output signal were calculated (Sample 2). Results areshown in FIG. 23 and FIG. 24 .

TEST EXAMPLE 3

Other than the length (T) in the Z direction of the first yoke unit 31(SY1) and the second yoke unit 32 (SY2) being 30 μm, the output signalfrom the magnetic sensor 1 was found through simulation the same as inTest Example 1, and the sensitivity of the magnetic sensor 1 and thehysteresis of the output signal were calculated (Sample 3). Results areshown in FIG. 23 and FIG. 24 .

TEST EXAMPLE 4

Other than the angle of inclination θ₃ of the first end surfaces 311 and321 and the second end surfaces 312 and 322 of the first yoke unit 31and the second yoke unit 32, and the angle of inclination 64 of thefirst facing surface 411 of the first bias magnetic field generationunit 41 and the second facing surface 412 of the second bias magneticfield generation unit 42 being 20°, 30°, 40°, 50°, 60°, 70° or 80°, theoutput signal from the magnetic sensor 1 was found through simulationthe same as in Test Example 1 using the magnetic sensor 1 having theconfiguration shown in FIGS. 5 ˜8B, and the sensitivity of the magneticsensor 1 and the hysteresis of the output signal were calculated (Sample4). Results are shown in FIG. 23 and FIG. 24 .

TEST EXAMPLE 5

Other than the length (T) in the Z direction of the first yoke unit 31(SY1) and the second yoke unit 32 (SY2) being 20 μm, the output signalfrom the magnetic sensor 1 was found through simulation the same as inTest Example 4, and the sensitivity of the magnetic sensor 1 and thehysteresis of the output signal were calculated (Sample 5). Results areshown in FIG. 23 and FIG. 24 .

TEST EXAMPLE 6

Other than the length (T) in the Z direction of the first yoke unit 31(SY1) and the second yoke unit 32 (SY2) being 30 μm, the output signalfrom the magnetic sensor 1 was found through simulation the same as inTest Example 4, and the sensitivity of the magnetic sensor 1 and thehysteresis of the output signal were calculated (Sample 6). Results areshown in FIG. 23 and FIG. 24 .

TEST EXAMPLE 7

Other than the protrusion length L43 of the first protruding part 43 ofthe first bias magnetic field generation unit 41 and the protrusionlength L44 of the second protruding part 44 of the second bias magneticfield generation unit 42 being 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm or 0.25μm, the output signal from the magnetic sensor 1 was found throughsimulation the same as in Test Example 3 using the magnetic sensor 1having the configuration shown in FIG. 9 , FIG. 10A, FIG. 11A and FIG.11C, and the sensitivity of the magnetic sensor 1 and the hysteresis ofthe output signal were calculated (Sample 7). Results are shown in FIG.25 and FIG. 26 .

TEST SAMPLE 8

Other than the angle of inclination 83 of the first end surfaces 311 and321 and the second end surfaces 312 and 322 of the first yoke unit 31and the second yoke unit 32, and the angle of inclination θ₄ of thefirst facing surface 411 of the first bias magnetic field generationunit 41 and the second facing surface 412 of the second bias magneticfield generation unit 42 being 50°, the output signal from the magneticsensor 1 was found through simulation the same as in Test Example 7, andthe sensitivity of the magnetic sensor 1 and the hysteresis of theoutput signal were calculated (Sample 8). Results are shown in FIG. 25and FIG. 26 .

In the graph shown in FIG. 23 , the vertical axis represents thenormalized sensitivity, and the horizontal axis represents the angle ofinclination 83 of the first end surface 311 and 321 and the second endsurface 312 and 322 and the angle of inclination 84 of the first facingsurface 411 and the second facing surface 412. In the graph shown inFIG. 24 , the vertical axis represents the normalized hysteresis, andthe horizontal axis represents the angle of inclination 83 of the firstend surface 311 and 321 and the second end surface 312 and 322 and theangle of inclination 84 of the first facing surface 411 and the secondfacing surface 412.

In the graph shown in FIG. 25 , the vertical axis represents thenormalized sensitivity, and the horizontal axis represents theprotrusion length L43 of the first protruding part 43 of the first biasmagnetic field generation unit 41 and the protrusion length L44 of thesecond protruding part 44 of the second bias magnetic field generationunit 42. In the graph shown in FIG. 26 , the vertical axis representsthe normalized hysteresis, and the horizontal axis represents theprotrusion length L43 of the first protruding part 43 of the first biasmagnetic field generation unit 41 and the protrusion length L44 of thesecond protruding part 44 of the second bias magnetic field generationunit 42.

As shown in FIG. 23 and FIG. 24 , it was confirmed that the larger thelength (T) in the Z direction of the first yoke unit 31 and the secondyoke unit 32, the more it is possible to improve the sensitivity of themagnetic sensor 1 and to reduce hysteresis of the output signal. Inaddition, it was confirmed that compared to having the first endsurfaces 311 and 321 and the second end surfaces 312 and 322 of thefirst yoke unit 31 and the second yoke unit 32 along with the firstfacing surface 411 of the first bias magnetic field generation unit 41and the second facing surface 412 of the second bias magnetic fieldgeneration unit 42 orthogonal to the XY plane (Samples 1-3), having thefirst end surfaces 311 and 321 and the second end surfaces 312 and 322along with the first facing surface 411 and the second facing surface412 inclined with respect to the XY plane (Samples 4-6) improved thesensitivity of the magnetic sensor 1 and reduced hysteresis of theoutput signal. In particular, it was confirmed that by having the angleof inclination 83 of the first end surfaces 311 and 321 and the secondend surfaces 312 and 322 along with the angle of inclination 84 firstfacing surface 411 and the second facing surface 412 be 40°˜70°, it ispossible to effectively improve the sensitivity of the magnetic sensor 1and to effectively reduce hysteresis of the output signal.

As shown in FIG. 25 and FIG. 26 , it was confirmed that by the firstbias magnetic field generation unit 41 having the first protruding part43 protruding toward the first end surface 23 of the magnetoresistiveeffect element 2 and the second bias magnetic field generation unit 42having the second protruding part 44 protruding toward the second endsurface 24 of the magnetoresistive effect element 2 (Samples 7 and 8),it is possible to improve the sensitivity of the magnetic sensor 1 andto reduce hysteresis of the output signal.

1. A magnetic sensor comprising: a magnetoresistive effect elementincluding a first side surface and a second side surface, which face inopposite directions along a first axis, and a first end surface and asecond end surface, which face in opposite directions along a secondaxis, wherein the first axis is substantially orthogonal to the secondaxis, and the magnetoresistive effect element has a sensitivity axisthat extends in a direction of the first axis; a first yoke unitprovided adjacent to the first side surface of the magnetoresistiveeffect element; a first bias magnetic field generation unit providedadjacent to the first end surface of the magnetoresistive effectelement; and a second bias magnetic field generation unit providedadjacent to the second end surface of the magnetoresistive effectelement; a substrate having a first surface; wherein the first biasmagnetic field generation unit is provided to be capable of applying abias magnetic field on the magnetoresistive effect element and the firstyoke unit.
 2. The magnetic sensor according to claim 1, wherein: thelength of the first bias magnetic field generation unit in the directionof the first axis is greater than a sum of the lengths of themagnetoresistive effect element and the first yoke unit in the directionof the first axis; and the magnetoresistive effect element and the firstyoke unit are provided to fit in a range of the length of the first biasmagnetic field generation unit in the first direction.
 3. The magneticsensor according to claim 1, further comprising a second yoke unitprovided adjacent to the second side surface of the magnetoresistiveeffect element.
 4. The magnetic sensor according to claim 3, wherein:the length of the first bias magnetic field generation unit in thedirection of the first axis is longer than a sum of the lengths of themagnetoresistive effect element, the first yoke unit and the second yokeunit in the direction of the first axis; and the magnetoresistive effectelement, the first yoke unit and the second yoke unit are provided tofit in a range of the length of the first bias magnetic field generationunit in the first direction.
 5. The magnetic sensor according to claim3, wherein the magnetoresistive effect element is one of a plurality ofthe magnetoresistive effect elements, and the magnetoresistive effectelements and either one of the first yoke unit or the second yoke unitare arranged alternatingly along the direction of the first axis.
 6. Themagnetic sensor according to claim 1, wherein the second bias magneticfield generation unit touches the second end surface of themagnetoresistive effect element.
 7. The magnetic sensor according toclaim 1, wherein the second bias magnetic field generation unit facesthe second end surface of the magnetoresistive effect element with aprescribed gap in between.
 8. The magnetic sensor according to claim 1,wherein the first bias magnetic field generation unit touches the firstend surface of the magnetoresistive effect element.
 9. The magneticsensor according to claim 1, wherein the first bias magnetic fieldgeneration unit faces the first end surface of the magnetoresistiveeffect element with a prescribed gap in between.
 10. The magnetic sensoraccording to claim 1, wherein the edge of the first bias magnetic fieldgeneration unit positioned on the magnetoresistive effect element sideoverlaps the end of the first yoke unit in the plan view of the magneticsensor.
 11. The magnetic sensor according to claim 10, wherein: thefirst bias magnetic field generation unit has a first facing surfacefacing the first end surface of the magnetoresistive effect element; thefirst facing surface is inclined at a prescribed angle with respect tothe second direction; and the first end surface of the first yoke unitfacing the first facing surface is inclined at a prescribed angle withrespect to the second direction.
 12. The magnetic sensor according toclaim 10, wherein: the edge of the second bias magnetic field generationunit positioned on the magnetoresistive effect element side overlaps theend of the first yoke unit in the plan view of the magnetic sensor. 13.The magnetic sensor according to claim 12, wherein: the second biasmagnetic field generation unit has a second facing surface facing thesecond end surface of the magnetoresistive effect element; the secondfacing surface is inclined at a prescribed angle with respect to thesecond direction; and the second end surface of the first yoke unitfacing the second facing surface is inclined at a prescribed angle withrespect to the second direction.
 14. The magnetic sensor according toclaim 1, wherein the first bias magnetic field generation unit has afacing surface that faces the first end surface of the magnetoresistiveeffect element and a protruding part that protrudes toward the first endsurface of the magnetoresistive effect element from the facing surface.15. The magnetic sensor according to claim 1, wherein the second biasmagnetic field generation unit has a facing surface that faces thesecond end surface of the magnetoresistive effect element and aprotruding part that protrudes toward the second end surface of themagnetoresistive effect element from the facing surface.
 16. Themagnetic sensor according to claim 1, wherein the magnetoresistiveeffect element includes a laminated body in which at least amagnetization fixed layer the magnetization of which is fixed, and amagnetization free layer the magnetization direction of which changes inaccordance with an external magnetic field, are layered.
 17. Themagnetic sensor according to claim 1, wherein the magnetoresistiveeffect element is an AMR element, a GMR element or a TMR element.
 18. Aposition detection device comprising: a magnetic detection unit thatoutputs a detection signal based on change in an external magnetic fieldaccompanying movement of a moving body; and a calculation unit thatcalculates an amount of movement of the moving body based on thedetection signal output from the magnetic detection unit, wherein themagnetic detection unit includes the magnetic sensor according toclaim
 1. 19. A current sensor comprising a magnetic detection unit thatdetects magnetism generated from a conductor in which a current to bemeasured flows, wherein the magnetic detection unit includes themagnetic sensor according to claim 1.